Alright, that's perfectly logical right there. The man, Mikael, expresses which bands are fundamental inspirations to his music, not to mention having a member from one work with him to orchestrate yet another Opeth album, and you expect Opeth fans to totally disregard this knowledge.. why?
Personally I feel the attitude Opeth fans demonstrate when following up on the band's musical tastes shows some level of insight. Obviously if a band you love, in turn love other artists, chances are that you will feel similarly.
I have absolutely NO IDEA why you seem to describe the general Opeth fan's ability to go further and look into related bands as a bad thing.
I have followed up on both Camel and Porcupine Tree after hearing Mikael praise them repeatedly in interviews... how does this make me a sheep? If a friend of mine told me about the same bands, would you still label me as one?
I love Camel, not because Mikael does, but because I think the music is great and surely stands against the test of time. Mikael is the REASON I know about them, but he is not the reason I enjoy their music. Same thing applies to Porcupine Tree who I don't even like... I actually think SW is a total fuckwad, but for some reason since it's because of Mikael that I know about SW and PT, I'm a sheep. Great thinking there ace.